Malkavian characters can be decidedly game breaking, especially when played well. I once created a centuries old Setite ghoul who had been turned by a Malkavian. His madness? He believed he was Ra, the sun god, and his new form was some vile trick performed by Set. He was a sun god now banned from daylight, robbed of much of his power. Needless to say, he did not find Setites to be good companions. He usually tried to capture them to find the whereabouts of Set and attempt to restore himself to godhood.

During the campaign the DM decided to introduce a Setite clan, and the local prince seemed to be bending over backwards to please them. This did not sit well with my character, and he started putting his connections to good use. Half of the party ended up joining him, the other half trying to stay loyal to the prince. The half that joined my character had some heavy connections as well... one was incredibly rich, the other was a night school teacher. She kept sending her students to my flock, where I was turning them into ghouls, and the wealthy one was supplying them with guns/armored vests. We went on a raid to wipe out the local group of Setites, and when the other half of the party tried to stop us, they were over-whelmed.

Sadly the game died out after that. I was very curious how the GM was going to handle the situation. But yeah... Power-mad (or mad in general) vampires who can sway some of the more resourceful party members over to his cause, which happens to be an inquisition... Definitely broke the game a touch.